Target-area-selection-type tube



J. A. RAJCHMAN TARGET-AREA-SELECTION-TYPE TUBE Jne 26, 1951 2 Sheets-Sheet l Filed Dec. 28, 1949 Gttorneg June 26, 1951 .J. A. RAJCHMAN 2,558,461

TRGETAREA-SELECTION-TYPE TUBE Filed Dec. 28, 1.949 2 sheets-sheet 2 snventor Cttorneg Patented .une I26, 1951 TARGET-AREA--SELECTION-TYPEy TUBE Jan A.. Rajchman, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application December 28, 1949, Serial No. 135,390

This invention relates to electron discharge devices o the target area selection type. More specifically this invention relates to any improved cathode and grid structure for electron discharge tube of the target area selection type.

Electron discharge tubes of the target area selection type are described and claimed in other applications by this applicant, Serial No. 665,031, led April 26, 1946, now Patent No. 2,494,670 issued January 17, 1950, and Serial No. 118,753, filed September 30, 1949, both for Electron Discharge Devices. These electron discharge dee vices are characterized by having a central source of electrons, a selecting grid which surrounds the electron source and target structure which envelops the above named structure. The storage portion of the target structure consists of a plurality of discrete storage areas usually regularly arranged in columns and rows. The selecting grid consists of a network of vertical conductors which are parallel, spaced and separately insulated and a network of horizontal conductors which are parallel, spaced and separately insulated. The selecting grid thus provides a plurality of rectangular openings or Windows which are opposed to the plurality of discrete storage areas of the targets. By controlling the bias applied to any one of the four conductors dening a window, it is possible to determine Whether or not electrons may pass from the electron source through that window to the opposed discrete target storage.

In operation, information is stored in each discrete storage area as a potential, either a cathode potential or a collector electrodepotential. In quiescent intervals, which occur between periods When the target is being written into or read, all the storage areas are bombarded by electrons. This serves as a locking mechanism to maintain all the storage areas at their potential and makes up losses due to leakage and other factors. The reading of information stored in the target is done While bombarding one storage area at a time and is evidenced by the presence or absence of a reading current in a reading tar get corresponding to the storage area being at collector or cathode potential. formation as to these processes reference should be made to the above indicated application.

Accordingly, it may be seen that it is advantageous to have as large an electron current flow` For complete in- 13 claims, (o1. 315-412) third, it serves as part of the reading mechanism and the larger the electron current the larger the obtainable reading current and the more accurate the reading.

The amount of current which it is possible to obtain from a source of electrons depends both on the power applied and the efficiency with which that power is used to direct the electrons to a desired location. Since the power, which a tube of a given size can dissipate is limited, too large tubes not being practical and being slower in operation, the efliciency of the electron current delivery is an important factor in electron discharge tubes of the storage target area selecting type. i

It is therefore an object of the present invention to provide an improved electron discharge device of the storage target area selecting type having a more eiiicient electron current delivery than heretofore.

It is a further object of the present invention to provide an improved electron discharge device of the storage target area selecting type having a greater electron current delivered to the storage target than heretofore.

It is still a further object of the present invention to provide a moreeicient cathode and accelerating grid structure for electron discharge tubes of the storage target area selecting type than heretofore.

These and other objects are achieved in accordance with my present invention by providing a storage target area selecting type of electron discharge device having a plurality of central, planar, spaced elongated cathodes each having a fluted quadrilateral shaped cross sectional area and emanating four focussed electron beams. Each of the cathodes are disposed so that one diagonal is at right angles to the cathode plane. Accelerating grid structure surrounds each of the cathodes. It is so shaped and positioned with respect to the cathodes that the four electron beams from each cathode are deflected and focussed so that they strike the target storage areas at an angle normal thereto.

In one embodiment of the invention portions of the accelerating grid between the cathodes are square and portions on either side of each cathode are pentagonal. Vertical conductors of the selecting grid are alternately given U and V shapes in order to assist the accelerating grid in deecting the electrons into a path normal to the discrete storage area of the target.

In a second embodiment of the invention the accelerating grid structure encloses each of the cathodes in a rectangular box with openings at the corners through which electrons pass to the targets. In a third embodiment of the invention the accelerating grid structure encloses each of the cathodes in a rectangular box and there are four openings provided in each box which are aligned with the discrete storage areas of the storage targets which enclose the tube structure.

The novel features of the invention, as well as the invention itself, both as to its organization and method of operation, will best be understood from the following description when read in connection with the accompanying drawings in which,

Figure l is a perspective view of the exterior of the electron discharge device, and

Figure 2 is a perspective View of an elongated cathode of the electron discharge device, and

Figure 3 is a cross-sectional view of the cathode, and

Figure 4 is a partial cross-sectional View of one embodiment of my present invention, and

v Figure 5 is a partial cross-sectional View of ann other embodiment of rny present invention, and Figure 6 is a partial cross-sectional View of still another embodiment of my present invention.

Referring to Figure l, there may be seen the elongated glass bulb i5 which encloses the tube structure and illustrates the general shape of the tube. Connections to the internal tube structure are made through stem leads I2 which are brought through the base of the bulb. The tube struc-- ture is supported by rods ill which are braced against the top and bottom of the inner side of the glass bulb It) in a manner well known to the art. The tube structure is contained within the rectangular shaped area I6 which conforms gen-- erally to the size of the target of the tube.

Figure 2 shows a perspective view of an elongated cathode I8. The cathode length is determined by the length of the storage target to be supplied with electrons. A cross-sectional view ofthe cathode i6 is shown in Figure 3 taken along the line 3-3 in Figure 2. The cathode consists of a base metal tubing 2B such as nickel tubingY having four equal uted sides 22, or the shape of a iluted, equilateral, quadrilateral 'coated with electron emissive material 2li. Centrally disposed within the cathode is the heater wire 26. This is surrounded by an insulator 28 such as conventional heater coating material on porcelain.V YThe uted cathode sides 22 enable a usage of the greatest part -of the cathode area and provide four, focussed electron beams. The number o cathodes required to provide coverage of a storage target is thereby kept at a minimum.

Referring to Figure 4, a partial cross-sectional View of a tube structure of one embodiment of my invention is shown taken along the line 3 5 shown in Figure l. It is to be noted that the tube structure is symmetrical having a central cathode plane wherein the cathodes I3 are positioned and the remaining tube structure is positioned on either side to sandwich the cathodes. Each cathode I8 is positioned so that one of its di agonals is normal to the cathode plane. An accelerating grid Si? encloses the cathodes i8, and includes square conductors 32 and pentagonal conductors 34. Alternate with and between the cathodes are the substantially square conductors 32 each of which is several times larger than a cathode and is positioned with one diagonal in the cathode plane. To facilitate outgasing the tube these conductors 32 are hollow. Spaced on either side of each cathode I8 is the pentagcnal conductor 34 which is also a part of the accelerating grid 3Q. The pentagonal conductor 34 has two equal sides at right angle to each other and making angles of 45 degrees with the plane f the cathodes and Serve as a vertex for the conductor. This vertex points toward an associated cathode i8. A plane, normal to the cathode plane and including a diagonal of a cathode included between two pentagonal conductors 35, passes through the vertices and bisects the two pentagu onal conductors.` The two sides of the pentagonal conductors 34 which are adjacent to the two sides forming the vertex are also of equal length and sweep back from the cathode plane making a slight angle with a line normal to that plane. Itis to be noted that the side of the pentagonal conductor opposed to the vertex is omitted. This is done because it serves no purpose at the rear of the conductor and by its omission and by making the conductor hollow the tube structure is considerably lightened and therefore easier to outgas.

rIwo square and two pentagonal conductors of the accelerating grid 3i! surround eachcathode and are coextensive with it. All the square and pentagonal conductors are connected together andserve as an accelerating electrode to which a potential is applied which is l5 to'60 volts posi-I tive with respect to the cathodes. This produces a positive gradient at the surface of the cathodes. Because of the curvature of the cathodes, the electrons are focussed into beams which for the most part passes through the channels between the squares and pentagons with only a small part being wasted on the accelerating grid itself.

On either side of the accelerating grid is a selecting grid 36. Each selecting grid has a network of vertical selecting conductors which are parallel to and co-extensive with the cathodes and a network of horizontal selecting conductoraat right angles to the cathodes. The vertic selecting conductors consist of U shaped conductors 33 which are positioned behind each pentagonal conductor 34 and V shaped conductors ifi which are spaced between the U shaped conductors 38. The' vertex of each V extends in the direction of an opposed square conductor and each V shaped conductor is bisected by a plane which passes through each opposed square con ductor and includes a diagonal of that square conductor which is normal to the cathode plane. The V shaped conductors'fl are parallel to and co-extensive with the cathodes. The base c each U shaped conductor 38 is toward the pentagonal conductor 34 behind which it is posi tioned. The U shaped conductors 33 are also parallel'to and co-extensive with the cathodes. BothrU and V shaped conductors are made hollow for lightness and their ends furtherest away from thercathodes terminate in a plane which is parallel to the cathode plane. It is to be noted that the sides of the V shapedconductors near the ends are parallel to the sides of the U shaped cone ductors. When a potential, which is applied te the V shaped conductors, bears a definite rela'- tion to the potential applied to the accelerating grid 3B of approximately twice that potential, the electron beams from the cathode are deflectei in the region between the pentagonal conductors` and the V shaped conductors by an angle of 45 deu grees and they then pass exactly in the center of the channels between the V and U shaped vertical conductors which are maintained at the same potential.

The network of horizontal selecting conductor. consists of a plurality of rectangular conductors [i2 which are all in a plane parallel to and spaced from each other and positioned at right angles'V toV the network of vertical conductors. The length of the horizontal conductors 42 is determined by the size of the plane formed by the vertical network in the direction of the length oi the horizontal conductors. The horizontal conductors are maintained at a potential somewhat higher than that applied to the vertical selecting bars but bearing no definite relation to it. When viewed from their outer side, the vertical and horizontal conductors of a selecting grid define a plurality of rectangular openings or windows the defining sides of which include two adjacent vertical conductors and two adjacent horibontal conductors. Electrons from the cathodes on the way to the target storage areas must pass through these windows. The theory of operation of a selecting grid, which permits the selection of any one window to be open to the passage of electrons while all others are closed, is described in detail in the above mentioned Patent No. 2,494,670. Briefly described, if two adjacent vertical conductors, which define two of the sides of a window which is desired to be left open to the passage of electrons, are biased at a potential which is positive with respect to the cathode (here approximately twice that of the accelerating grid), and if the two adjacent horizontal selecting conductors, defining the other two sides of the desired window, are also biased suitably positive (here this potential is slightly higher than the vertical conductor potential), then electrons may pass through the desired window. Should any one of the window dening selecting bars be made negative the electrons are deflected and will not pass through that window. Thus, by bringing out leads from each of the vertical 38, 4|] and horizontal conductors 42 and by application of the proper bias to those leads, complete control of the passage of electrons through any of the Windows may be effectuated. Methods for effecting complete control of the electron stream utilizing a number of external leads which is less than the number of individual grid Wires have been described and claimed in a copending application of J. A. Rajchman, Serial No. 702,775, filed October 11, 1946 and the application of George W.,Brown, Serial No. 694,041, iiled August 30, 1946 now Patent No. 2,519,172 issued August l5, 1950, and assigned to a common assignee.

Positioned on the outer side of each of the selecting grids 3'6 and parallel to the cathode plane are a first 43 and second 55 target assembly. These target assemblies are described and claimed in an application by Jan A. Rajchman for a Target for Storage Tubes, Serial No. 122,657, led October 15, 1949. The iirst target assembly consists of a collector electrode 44 which includes two flat metal plates perforated with round holes, the centers of which are aligned with the centers of the windows formed by the vertical and horizontal selecting bars. The rst plate, which is nearest the horizontal selecting bars, is known as the collector mask 46 and has the smaller holes. The second plate, or collector spacer 48, is in intimate contact with the collector mask and has the larger holes.

Two parallel,V spaced, insulating material sheets, 50, such as mica, are positioned adjacent the outer side of the collector electrode 44. These sheets are perforated and support between them, in the perforations, metallic storage eyelets 52. The perforations are made so that the eyelets 52 are supported with their openings opposite the center of a selecting grid window. The eyelets 52 are generally cylindrical and haveshoulder offset portions to be insulatindgly retained thereby by the perforated mica sheets. Another metallic plate known as the writing plate 54 is positioned adjacent the outer insulating sheet 50 and has perforations which are aligned with the storage eyelets 52. The writing plate is separated from the eyelets by the insulating material sheet and serves as a common capacity plate for all the eyelets.

A second target assembly 55 is spaced from the outer side of each of the first target assemblies. Each second target assembly 55 includes a reading plate 56 which is a metal plate having perforations aligned with the storage eyelets. Spaced from the reading plate is a Farady cage 58. This is a rectangular metallic box in which two walls are parallel to the reading plate 56 and have perforations aligned with the reading plate perforations. A glass plate 60 coated with a fluorescent and secondary electron emitting material 62, such as willemite is placed against the outer perforated wall of the Faraday cage 58. In the central plane of the cage there are a number of reading wires 64 which are positioned so that they are between the perforations in the perforated walls and are thus shielded from any electrons which may be coming directly from the target as well as any electrostatic field leakage from the reading plate. These reading wires are connected together and the corresponding lead to the stem of the tube is shielded.

The operation of the above described electron discharge tube is substantially similar to the operation of the target area selecting type of tube described and claimed in my copending application, Serial No. 118,758, filed September 30, 1949. In the quiescent condition of the tube the vertical and horizontal selecting bars are all at the proper biasing Apotential to permit passage of electrons through each of the windows to strike each of the storage eyelets.

|The act of reading or Writing requires the selection of one eyelet or target element (two eyelets if the two halves of the tube are run in parallel). This selection is obtained by applying a negative pulse to one or more of the selecting bars defining all the windows except to the selecting bars defining the window which is left open.

For positive writing, after selection, a highly positive pulse is applied to the writing plate and is then allowed to slowly subside. The eyelet selected then remains at collector potential. For negative Writing, after selection, a highly positive pulse is applied, but before it can subside the electron stream to the eyelet is cut oil by applying a negative pulse to one of the four dening selecting conductors of the one open window. After the end of the highly positive pulse, all other pulses are ended and current is ree'stablished to all the eyelets.

The reading or interrogating of the tube constituting an embodiment of my invention is done by first closing all windows except the one opposite the storage eyelet whose condition is to be read. Some arbitrary short safety period thereafter, a positive reading pulse is applied to the reading plate which was previously negatively biased. If the selected storage eyelet is at collector potential electrons will pass through the storage eyelet into the Faraday cage where they strike the secondary emissive and fluorescent material through the hole in the Faraday cage wall causing fluorescence in the hole area and the release of secondary electrons which are then collectedby the reading wires and cause a pulse of reading current in the reading wires. However, if the selected eyelet is at cathode potential noV electron current passes through the storage eyelet and therefore no current will be detected in the reading wires. The target described and shown is merely by way of illustration and is not a part of this invention. Any of the other storage targets which are also shown and described in my cope-riding application for an Electron Storage Device with Grid Control Action, Serial No.' 722,194, iiled January l5, 1947, now Patent No. 2,513,743 issued July 4, 1950, may be used instead. A requirement for the storage target used is that its discrete storage areas must be in rows and columns which are aligned with the windows of the selecting grid. The cathodes are usually positioned to be between alternate ones of said rows. The number of cathodes and their length as well as the number of conductors and their lengths for both the selecting grids and the accelerating grid are Ivariable and are determined by the size of the storage target and the number of discrete storage elements contained therein.

It will be noticed that electron beams from adjacent cathodes cross each other in the regions between the pentagonal conductors. This effect produces no mutual interaction between the beams because of the extremely small size of the electrons and the negligible space charge effects. The reason for introducing such crossing is the fact that the beams are badly de- -focused if deflected the appreciable angle of 45 degrees on too short a radius. If a reasonably large radius were used the tube would become unreasonably large and therefore the expedient of the crossings was resorted to.

Also illustrated in Figure 4 are some electron trajectories shown as lines with arrows for the condition when the Windows are open. When any of the V conductors of a selecting grid are made negative the electron beams from the cathodes are deflected into the pentagonal conductors. 'If a V shaped conductor is made positive and the adjacent U shaped conductor is made negative, the electron beam is then deflectecl into the V shaped conductor. When both adjacent U and V shaped conductors are positive the electrons pass between them and if the eyelet is being read and is at collector potential the electrons continue to pass through the eyelet, through the Faraday cage and finally strike the willernite coating. The liberated secondary electrons, having a trajectory depicted as a dotted line, are drawn to the reading wires. This target operation is more fully described in the applicatic-n for a Target for Storage Tubes, identied above.

Support for the structure inside the glass envelope of the above described embodiment of my invention may be made in any manner well known to the art. External connection to the structures inside the envelope may be made through leads brought out through the base of the tube also in a manner well known to the art.

Referring now to Figure 5, another embodiment of my invention is shown in which the same cathode and target structure as are shown and described in Figure 4 are used. The View of the embodiment of my invention shown is a partial axial cross section also taken along the line 4-4 of Figure l. In this embodiment of the invention the various structural elements of the tube are also symmetrically disposed on either side of the central cathode plane.

The accelerating grid 6B is box like and servesto enclose each of the cathodes in a rectangular box with openings at the corners through which the electrons pass. VTwo metalY plates 68 are spaced on either side of the cathodes I8 and parallel to the cathode plane. The metal plates t8 are longer than the elongated cathodes and suilicientlyvwider to permit total enclosure of the cathodes and retention by supporting structure (not shown) at the' sides. The metal plates 63 are positioned on either side of the cathodes substantially just before the focused electron beams from adjacent cathodes cross each other. Rectangular openings are provided in the plates to permit passage therethrough of the focused beams. Completing the box like accelerating grid structure G6 are a plurality of rectangular conductors l0 each of which is centrally positioned between adjacent cathodes to be bisected by the cathode plane and is coextensive with the cathodes. The thickness and width dimensions of the rectangular conductors l0 are also determined so that they will not interfere with the focused electron beams of adjacent cathodes. The rectangular conductors lll are provided with a series of lingers (not shown), by means of which they are welded to the flat plates to be supported thereby. The accelerating grid 66 is biased about 15 Volts more positive than the cathodes. Spaced on either side of the iiat plates of the accelerating grid is a selecting grid 12 including vertical 14 and horizontal 'I6 selecting conductors. The vertical selecting conductors 14 of this grid are rectangular conductors which are spaced, parallel to each other and to the cathode plane, are individually insulated, and are coextensive with the cathodes. The vertical selecting conductors 'M are disposed so that alternate ones are aligned with the rectangular conductors l0 of the accelerating grid 66 and the remaining ones of the vertical selecting conductors are aligned with those diagonals of the cathodes which are at right angles to the cathode plane. The horizontal selecting conductors 16 are rectangular conductors which are spaced, parallel, separatelyv insulated and at right angles to the vertical conductors. As in the first embodiment of my invention the Yconductors of the selecting grid denne a plurality of windows through Whichelectrons from the cathodes pass from the cathodes to the target. Opening and closing of the windows may be obtained by the proper selection of the bias applied to the conductors deiining the windows.

AIn addition to the function of vertical selection the vertical selecting conductors 'I4 also assist in bending the electron streams from the various cathodes so that they will pass through the windows'of the Selecting grid to strike the target storage areas at right angles. For this purpose, alternate vertical selecting conductors are biased at a higher potential of approximately 70 volts positive with respect to the cathodes and the remaining ones are biased at a lower potential of approximately 50 vlolts positive with respect to the cathode. Therhorizontal selecting conductors are allmaintained at a potential of approximately 100 volts positive with Vrespect to the cathode.

'Ihe first and second target assemblies are the same jas described above for Figure 4, and need not be redescribed. All apertures and discrete storage areas are aligned with .the windows dened by `the selecting grid conductors. The operation of this embodiment of .my invention for writing and reading is the same as for 'the embodiment previously described. A few typical electron beam trajectories are represented in Figure for the condition when the windows are open. It can be readily seen how the two focussed electron beams from two adjacent cathodes cross each other approximately outside the plane of the flat plates S8 of the accelerating grid 66 and are then bent by the vertical selecting conductors 'I4 to pass through each of the windows to be normal to the respective opposed discrete storage areas.

Figure 6 represents another embodiment of my invention using the same cathode and target structure as described previously herein. A iirst accelerating grid I8 structure consists of two ilat plates 80 positioned on either side of the cathodes I8 to enclose them. Alternate with the cathodes and positioned between them are rectangular conductors, 82, also part of the first accelerating grid 18, which are bisected by the cathode plane. On either side of the flat plates 8l) is a selecting grid 84 having vertical selecting conductors 86 and horizontal selecting conductors 88 which are rectangular and are disposed similarly with respect to each other and the cathodes and target as are the vertical and horizontal selecting conductors shown in Figure 5. However, a second accelerating grid 90, consisting of a flat plate having a plurality of perforations aligned with the windows defined by the selecting grid conductors, is interposed between the horizontal 88 and vertical selecting 8B grid conductors. A rst target assembly 43 and a second target assemblyr55 are positioned on the outer sideA of each selecting grid and the collector holes and discrete storage areas are also aligned with the selecting grid windows.

The flat plates 80 which are a part of the rst accelerating grid structure also have apertures which are aligned with the windows of the selecting grid 84. The rectangular conductors B2 of the first accelerating grid have a thickness which is substantially equal to the distance between the apertures in the at plates. These rectangular conductors serve to deflect the electron streams from the cathodes into the holes in the flat plates. An alternative description of the structure shown in Figure 6 is that the perforations in the two plates 8U of the first accelerating grid 18, the perforations of the plate of the second accelerating grids 90 and the windows of the selecting grids 84 are all aligned with the discrete storage areas of the targets. These discrete storage areas are arranged in parallel rows and columns. Each of the cathodes I8 is positioned between alternate columns. Each of the first accelerating grid rectangular conductors 82 is alternate with a cathode I8 and together with the two flat plates 8l] serves to enclose each cathode I8' in a rectangular box having openings at the corners through which electrons from the cathode may pass. Some typical tube bias values are, 17 volts above the cathodes for the rectangular conductors of the first accelerating grid,` '74 volts above the cathodes for the at plates,`

220 volts above the cathodes for the vertical selecting conductors, 660 volts above the cathodes for the second accelerating grids, 660 volts positive above the cathode for the horizontal selecting grid, and 200 to 600 volts above the cathode for the collector potential.

Typical electron trajectories are shown in Figure 6 for the situation where the windows are open illustrating how the cathode beam is deflected by the rectangular conductors through 10 the holes in the rst accelerating grid plates and how any beam divergence 'is further corrected by the second accelerating grid.

The operation of this embodiment of my invention for reading, writing, and discrete target area selection is the same as for the previously described embodiments of my invention and need not be redescribed here.

From the foregoing description, it will be readily apparent that I have provided an improved electronic discharge device of the storage target area selecting type wherein a row of fluted cathodes are used, each supplying four electron beams which are deflected so that they strike the discrete storage areas of the target normally, thus providing a more eilicient selected electron current delivery. Although several embodiments of my invention have been shown and described, it should be apparent that many changes may be made in the particular embodiments herein disclosed, and that many other embodiments are possible, all within the spirit and scope of my invention. Therefore, I desire that the foregoing description be taken as illustrative and not as limiting.

What is claimed is:

1. An electron discharge tube of the type having a central planar source of electrons, :a grid structure on either side of said planar source of electrons and a target structure on either side of said grid structure, said planar source of electrons comprising a plurality of spaced, parallel coplanar elongated cathodes, each of said cathodes having the cross-sectional area of a polygon with fluted sides, a portion of said grid structure comprising an accelerating grid which surrounds each one of said cathodes and in which openings in said grid are provided between each of said cathodes to permit the flow of electrons therethrough to each of said targets from each of said cathodes.

2. An electron discharge tube of the type having a central planar source of electrons, a grid structure on either side of said planar source of electrons and a target structure on either side of said grid structure, said planar source of electrons comprising a plurality of spaced, parallel coplanar elongated cathodes, each of said cathodes having the cross-sectional area of a quadrilateral with equal iluted sides to provide four focussed electron beams, a portion of said grid structure comprising an eccelerating grid which surrounds each one of said cathodes and in which openings in said grid are provided between each of said cathodes to permit the ow of lelectrons therethrough to each of said targets from each of said cathodes.

3. An electron discharge tube of the type having a central planar source of electrons, a planar storage target presented to either side of saidj planar source of electrons and a grid structure disposed on either side of said source of electrons and between said source of electrons and said target, wherein said planar source of electrons comprises a plurality of spaced, parallel, coplanar, elongated cathodes, each of said. cathodes having the cross sectional area of a quadrilateral with equal fluted sides to provide four focussing electron emitting surfaces and being positioned to have one diagonal of said quadrilateral perpendicular to both said planar storage targets.

4. An electron discharge tube of the type having a central planar source of electrons, a planar storage target presented to either side of said4 planar source of electrons and a grid structure disposed on either side of said source oi electrons and between said source of electrons and said target, wherein said planar source of electrons comprises a plurality of spaced, parallel, coplanar, elongated cathodes, each of said cathodes having the cross-sectional area of a quadrilateral with equal iluted sides to provide four focussing electron emitting surfaces and being positioned to have one diagonal of said quadrilateral perpendicular to both said planar storage targets, and said grid structure includes accelerating grid means to deilect the electrons emitted from said four electron emitting surfaces to strike normally said planar storagevtargets.

5. An electron discharge tube as recited in claim 4, wherein said accelerating grid means includes elongated conductors, each of which is dispose-d between adjacent ones ci said plurality of spaced cathodes and are coextensive therewith, and other conductors disposed on either side of each of the plane of said cathodes and being parallel to and coextensive with said cathodes. g

6. An electron dischargetube having a central planar source of electrons, an accelerating grid having portions interposed within and on either side of said planar source of electrons, a pair of selecting grids enclosing said accelerating grid Aand source of electrons, and a pair oi storage targets, each one being presented to the outer side of each of said selecting grids and having a plurality of discrete storage areas.

,7. An electron discharge tube having a central planar source of electrons, a first accelerating grid having portions interposed within and on either side of said source of electrons, a pair of selecting grids which enclose said rst accelerating grid and said source of electrons, each of said selecting grids including a network of vertical selecting conductors and a network of horizontal selecting conductors, a pair of second accelerating grids, each of said second accelerating grids being positioned between one of said vertical and horizontal selecting wire networks, and a pair of storage targets, each one of which is presented to the outer side of each of said selecting grids, said targets being of the type having a plurality of discrete storage areas.

8. An electron discharge tube of the storage target area selecting type comprising a plurality of spaced, parallel, planar elongated cathodes, each having a iluted equilateral quadrilateral cross sectional area and being positioned to have one of its diagonals perpendicular to the plane of said cathodes, accelerating grid means on either side of and between said plurality of cathodes to deect electrons from each of said cathodes to a path normal to said cathode plane, a pair of selecting grids disposed on either side of and parallel to said cathode plane, and a pair of storage targets disposed on either side of said selecting grids and parallel to said cathode plane.

9. A cathode and accelerating grid structure for an electron discharge tube, said cathode structure comprising a plurality of spaced, parallel, planar, elongated cathodes, each having a, luted equilateral, quadrilateral cross sectional, area, and being positioned to have one of its diagonals perpendicular to the plane of said cathodes, said accelerating grid structure comprising a plurality of square conductors, each of said conductors alternating and being coex i2 tensive with each of said cathodes and being between said cathodes, said conductors being positioned to have one diagonal perpendicular to the plane of said cathodes, and a plurality of pentagonal conductors coeXtensive with said cathodes, each of said pentagonal conductors having two sides of equal length and making an angle of degreeswith each other to form an apex, one of said pentagonal conductors, ,being positioned on either side of each oi said cathodes so that a plane containing theV diagonal of said cathode normal to said cathode plane passes through and bisects each of said pentagonal conductors apices and said pentagonal conductors.

10. A cathode and accelerating grid structure for an electron discharge tube, said cathode structure comprising a plurality of spaced parallel planar elongated cathodes each having a fluted equilateral, quadrilateral cross sectional area providing four focussed electron beams and being positioned to have one of'its diagonals perpendicular to the plane of said cathodes, said accelerating grid structure compris-ing a plurality of rst rectangular conductors, each of said conductors alternating and being coextensive with and between said cathodes and being perpendicular to and bisected by said cathode plane, and a pair of conductive fiat plates positioned parallel to said cathode plane, coeXten-Vsive with and'enclosing said cathodes, said plates having a plurality of rectangular openings which are opposed to and slightly wider than the dimension of each of said rst conductors presented to said dat plates, said first conductors and said flat plates enclosing each of said cathodes in a rectangular box having openings at the corners through which the focussed electron beams emitted by each of said cathodes may pass.

1l. An electron discharge tube having a central planar source of electrons, an accelerating grid having portions interposed between and on either side of said planar source of electrons, a pair of selecting grids which enclose said accelerating grid, and a pairV of storage targets, each one being presented to the, outer side of each of said selecting grids, each of said targets being of the type having a plurality of discrete storage areas disposed in substantially parallel rows, said discrete storage areas of one of said targets being aligned with the discrete storage areas of the other of said targets, wherein said planar source of electrons includes a plurality of spaced, parallel, planar, elongated cathodes, each having a luted equilateral, quadrilateral cross sectional area, each being positioned to ing an angle of 90 degrees with each other to vform an apex, one of said pentagonal conductors being pos-itioned o'n either side of each of said cathodes so that a plane containing the diagonal of said cathode normal to said cathode plane passes through and bisects each of said pentagonal conductors apices and pentagonal 13 conductors; and wherein each of said selecting grids comprises a plurality of separately insulated spaced U shaped and V shaped Vertical seiecting conductors, each or said V shaped co-nductors being spaced from one of said square conductors and positioned with its apex toward said square conductor and positioned to be bisected by a plane which includes a diagonal of said square conductor and is at right angles to said cathode plane, each of said U shaped coni ductors being spaced from a pentagonal cond-uctor and being positioned with the bottom of said U closest to and parallel to said cathode plane and to be bisected by said plane bisecting said pentagonal conductor, said U and V shaped conductors being parallel to and coextensive with said cathodes, and a plurality of separately insulated spaced parallel horizontal selecting conductors coextensive with said targets and together with said vertical selecting conductors dening a plurality of windows opposed to said plurality of discrete storage areas and through which electrons from said cathodes may pass to said storage areas.

12. An electron discharge tube having a central planar source of electrons, an accelerating grid having portions interposed within and on either side of said planar source of electrons, a pair of selecting grids which enclose said accelerating grid and source of electrons, and a pair of storage targets, each one being presented to the outer side of each of said selecting grids; each of said targets being of the type having a plurality of discrete storage areas disposed in substantially parallel columns, said discrete storage areas of one of said targets being aligned with the discrete storage areas of the other of said targets, wherein said planar source of electrons includes a plurality of spaced, parallel planar, elongated cathodes, each having a liuted equilateral, quadrilateral cross sectional area, each being positioned to have one of its diagonals perpendicular to the plane of said cathodes, and each of said cathodes being disposed between alternate ones of said parallel columns of discrete storage areas of said targets; wherein said accelerating grid comprises a plurality of rst rectangular conductors, each of said conductors alternating and being coextensive with each of said cathodes and being positioned to be perpendicular to and bisected by said cathode plane, and a pair of conductive nat plates positioned parallel to and spaced from said cathode plane, coextensive with and enclosing said cathodes, each of said plates having a plurality of rectangular openings which are opposed to and slightly wider than the dimension of each of said rst conductors presented to said plates, said rst conductors and said flat plates enclosing each of said cathodes in a rectangular box having openings at the corners through which electrons emitted by each of said cathodes may pass; and wherein each of said selecting grids comprises a plurality of separately insulated, spaced, parallel, rectangular, vertical conductors, said vertical conductors being spaced from said rst conductors, coextensive with said cathodes and perpendicular to said cathode plane, each of said vertical conductors being positioned between said parallel columns of discrete storage areas, and a plurality of separately insulated, spaced, parallel, rectangular, horizontal selecting conductors coextensive with said target and together with said vertical selecting conductors defining a plurality of windows each of which is i4 opposed to one of said plurality of discrete storage areas and through which electrons from said cathodes may pass to said discrete storage areas.

13. An electron discharge tube having a central planar source of electrons, a iirst accelerating grid having portions interposed within and on either side oi said planar source of electrons, a pair of selecting grids which enclose said first accelerating grid and said electron source, each of said selecting grids having a network of vertical selecting wires and a network of horizontal selecting wires, a pair of second accelerating grids, each oi said pair of second grids being positioned between one of said vertical and said horizontal selecting wire networks and a pair of storage targets, each one being presented to the outer side ci each or said selecting grids, each of said targets being of the type having a plurality of discrete storage areas disposed in substantially parallel columns, said discrete storage areas of both said targets being in alignment with each other, wherein said planar source of electrons includes a plurality of space-d, parallel, planar, elongated cathodes, each having a iluted, equilateral, quadrilateral cross sectional area, each 'being positioned to have one of its diagonals perpendicular to the plane of said cathodes, and each of said cathodes being disposed between alternate ones of said parallel rows of discrete storage areas; wherein said rst accelerating grid comprises a pair of conductive flat plates positioned parallel to said cathode plane, coextensive with and enclosing said cathodes, each of said plates having a plurality of apertures aligned with each of said discrete storage areas, and a plurality of rst rectangular conductors, each of said conductors alternating with and being coextensive with each of said cathodes and being positioned between adjacent apertures in one of said flat plates and to be perpendicular to and bisected by said cathode plane; wherein said network of vertical selecting wires of each of said pair of selecting grids includes a plurality of separately insulated, spaced parallel, rectangular conductors, coextensive with said cathodes and each of said conductors being positioned between said aligned rows of discrete storage areas, and said network of horizontal selecting wires of each of said pair of selecting grids includes a plurality of separately, insulated spaced, parallel rectangular conductors, coextensive with said target and together with said vertical selecting wires defining a plurality of windows each of which is opposed to one of said plurality of discrete storage areas and through which electrons from said cathodes may pass to said discrete storage areas; and wherein each of said pair of second accelerating grids comprises a at plate having a plurality of openings aligned with said plurality of discrete storage areas.

JAN A. RAJCHMAN.

REFERENCES CITED The following references are of record in the lle of this patent:

UNITED STATES PATENTS Number Name Date 2,201,880 Bruce May 21, 1940 2,459,072 Haines Jan. 11, 1949 2,494,670 Rajchman Jan. 17, 1950 2,513,743 Rajchman July 4, 1950 

